The Ectatic Aorta: No Benefit in Surveillance

Abstract

Conclusion: Patients with an abdominal aorta diameter of between 25 and 30 mm identified on a screening study for possible abdominal aortic aneurysm (AAA) do not require further surveillance for at least 5 years. Summary: Ultrasound screening of men aged ≥65 years appears effective in reducing AAA-related mortality and cost (Ashton HA, et al, Lancet 2002:360:1531-9). There is, however, little consensus on follow-up of the so-called ectatic aorta. This study defined an ectatic aorta as 25 to 30 mm in anterior-posterior (AP) diameter. As many as one-third of the patients screened for AAA will have an “ectatic” aorta (Devaraj S, et al, Ann R Coll Surg Engl 2008;90:477-82). The authors sought to determine if patients with aortic diameters between 25 and 30 mm should have continued surveillance or if they could be discharged from follow-up ultrasound screening. This was a retrospective study of data prospectively collected as part of a Liecestershire AAA screening program. The program has been in place since 1996 and screens men aged >65 years with a single ultrasound scan of the aorta. Patients with an AP diameter of the aorta <25 mm are discharged from further screening. Those with aortas >25 mm in diameter enter the surveillance program, with ultrasound scans every 12 months in patients with aortas of 25 to 29 mm, every 6 months in patients with aortas between 30 and 49 mm, and every 3 months when the aortic diameter is between and 50 and 52 mm. For this study, the authors used patients with an initial AAA diameter of 25 to 30 mm who had undergone two or more surveillance scans. There were 345 patients analyzed and the primary end point was death from AAA rupture, presentation with rupture, or referral for elective repair. The mean follow-up was 4.25 years (range, 1-11 years). At 5 years of surveillance, there was a 97% freedom from death from rupture or referral for repair. Comment: For screening to be both effective and cost effective there must be identification of appropriate subgroups of patients where a reasonable yield of the screening process is anticipated. One can certainly argue over what is “a reasonable yield.” However, it is difficult to argue that continued close surveillance of patients with abdominal aortas between 25 and 30 mm has any hope of being cost effective. The information provided here should be useful for those designing and implementing AAA screening programs in their communities.